DOCSLIB.ORG

Guide to Cone Penetration Testing

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Guide to Cone Penetration Testing GUIDE TO CONE PENETRATION TESTING www.greggdrilling.com Engineering Units Multiples Micro (μ) = 10-6 Milli (m) = 10-3 Kilo (k) = 10+3 Mega (M) = 10+6 Imperial Units SI Units Length feet (ft) meter (m) Area square feet (ft2) square meter (m2) Force pounds (p) Newton (N) Pressure/Stress pounds/foot2 (psf) Pascal (Pa) = (N/m2) Multiple Units Length inches (in) millimeter (mm) Area square feet (ft2) square millimeter (mm2) Force ton (t) kilonewton (kN) Pressure/Stress pounds/inch2 (psi) kilonewton/meter2 kPa) tons/foot2 (tsf) meganewton/meter2 (MPa) Conversion Factors Force: 1 ton = 9.8 kN 1 kg = 9.8 N Pressure/Stress 1kg/cm2 = 100 kPa = 100 kN/m2 = 1 bar 1 tsf = 96 kPa (~100 kPa = 0.1 MPa) 1 t/m2 ~ 10 kPa 14.5 psi = 100 kPa 2.31 foot of water = 1 psi 1 meter of water = 10 kPa Derived Values from CPT Friction ratio: Rf = (fs/qt) x 100% Corrected cone resistance: qt = qc + u2(1-a) Net cone resistance: qn = qt – σvo Excess pore pressure: Δu = u2 – u0 Pore pressure ratio: Bq = Δu / qn Normalized excess pore pressure: U = (ut – u0) / (ui – u0) where: ut is the pore pressure at time t in a dissipation test, and ui is the initial pore pressure at the start of the dissipation test Guide to Cone Penetration Testing for Geotechnical Engineering By P. K. Robertson and K.L. Cabal (Robertson) Gregg Drilling & Testing, Inc. 4th Edition July 2010 Gregg Drilling & Testing, Inc. Corporate Headquarters 2726 Walnut Avenue Signal Hill, California 90755 Telephone: (562) 427-6899 Fax: (562) 427-3314 E-mail: [email protected] Website: www.greggdrilling.com The publisher and the author make no warranties or representations of any kind concerning the accuracy or suitability of the information contained in this guide for any purpose and cannot accept any legal responsibility for any errors or omissions that may have been made. Copyright © 2010 Gregg Drilling & Testing, Inc. All rights reserved. TABLE OF CONTENTS Glossary i Introduction 1 Risk Based Site Characterization 2 Role of the CPT 3 Cone Penetration Test (CPT) 6 Introduction 6 History 7 Test Equipment and Procedures 10 Additional Sensors/Modules 11 Pushing Equipment 12 Depth of Penetration 17 Test Procedures 17 Cone Design 20 CPT Interpretation 24 Soil Profiling and Soil Type 25 Equivalent SPT N60 Profiles 31 Soil Unit Weight () 34 Undrained Shear Strength (su) 35 Soil Sensitivity 36 Undrained Shear Strength Ratio (su/'vo) 37 Stress History - Overconsolidation Ratio (OCR) 38 In-Situ Stress Ratio (Ko) 39 Friction Angle 40 Relative Density (Dr) 42 Stiffness and Modulus 44 Modulus from Shear Wave Velocity 45 Estimating Shear Wave Velocity from CPT 46 Identification of Unusual Soils Using the SCPT 47 Hydraulic Conductivity (k) 48 Consolidation Characteristics 51 Constrained Modulus 54 Applications of CPT Results 55 Shallow Foundation Design 56 Deep Foundation Design 79 Seismic Design - Liquefaction 91 Ground Improvement Compaction Control 116 Design of Wick or Sand Drains 119 Software 120 Main References 123 CPT Guide – 2010 Glossary Glossary This glossary contains the most commonly used terms related to CPT and are presented in alphabetical order. CPT Cone penetration test. CPTu Cone penetration test with pore pressure measurement – piezocone test. Cone The part of the cone penetrometer on which the cone resistance is measured. Cone penetrometer The assembly containing the cone, friction sleeve, and any other sensors, as well as the connections to the push rods. Cone resistance, qc The force acting on the cone, Qc, divided by the projected area of the cone, Ac. qc = Qc / Ac Corrected cone resistance, qt The cone resistance qc corrected for pore water effects. qt = qc + u2(1- a) Data acquisition system The system used to record the measurements made by the cone. Dissipation test A test when the decay of the pore pressure is monitored during a pause in penetration. Filter element The porous element inserted into the cone penetrometer to allow transmission of pore water pressure to the pore pressure sensor, while maintaining the correct dimensions of the cone penetrometer. Friction ratio, Rf The ratio, expressed as a percentage, of the sleeve friction, fs, to the cone resistance, qt, both measured at the same depth. Rf = (fs/qt) x 100% i CPT Guide - 2010 Glossary Friction reducer A local enlargement on the push rods placed a short distance above the cone penetrometer, to reduce the friction on the push rods. Friction sleeve The section of the cone penetrometer upon which the sleeve friction is measured. Normalized cone resistance, Qt The cone resistance expressed in a non-dimensional form and taking account of the in-situ vertical stresses. Qt = (qt – vo) / 'vo Normalized cone resistance, Qtn The cone resistance expressed in a non-dimensional form taking account of the in-situ vertical stresses and where the stress exponent (n) varies with soil type and stress level. When n = 1, Qtn = Qt. n q t vo Pa Qtn = Pa2 'vo Net cone resistance, qn The corrected cone resistance minus the vertical total stress. qn = qt – vo Excess pore pressure (or net pore pressure), u The measured pore pressure less the in-situ equilibrium pore pressure. u = u2 – u0 Pore pressure The pore pressure generated during cone penetration and measured by a pore pressure sensor: u1 when measured on the cone face u2 when measured just behind the cone. Pore pressure ratio, Bq The net pore pressure normalized with respect to the net cone resistance. Bq = u / qn Push rods Thick-walled tubes used to advance the cone penetrometer Sleeve friction, fs The frictional force acting on the friction sleeve, Fs, divided by its surface area, As. fs = Fs / As ii CPT Guide – 2010 Introduction Introduction The purpose of this guide is to provide a concise resource for the application of the CPT to geotechnical engineering practice. This guide is a supplement and update to the book ‘CPT in Geotechnical Practice’ by Lunne, Robertson and Powell (1997). This guide is applicable primarily to data obtained using a standard electronic cone with a 60-degree apex angle and either a diameter of 35.7 mm or 43.7 mm (10 or 15 cm2 cross-sectional area). Recommendations are provided on applications of CPT data for soil profiling, material identification and evaluation of geotechnical parameters and design. The companion book provides more details on the history of the CPT, equipment, specification and performance. A companion Guide to CPT for Geo-environmental Applications is also available. The companion book also provides extensive background on interpretation techniques. This guide provides only the basic recommendations for the application of the CPT for geotechnical design A list of the main references is included at the end of this guide. A more comprehensive reference list can be found in the companion CPT book. 1 CPT Guide - 2010 Risk Based Site Characterization Risk Based Site Characterization Risk and uncertainty are characteristics of the ground and are never fully eliminated. The appropriate level of sophistication for site characterization and analyses should be based on the following criteria: Precedent and local experience Design objectives Level of geotechnical risk Potential cost savings The evaluation of geotechnical risk is dependent on hazards, probability of occurrence and the consequences. Projects can be classified as either low, moderate or high risk, depending on the above criteria. Table 1 shows a generalized flow chart to illustrate the likely geotechnical ground investigation approach associated with risk. The level of sophistication in a site investigation is also a function of the project design objectives and the potential for cost savings. Table 1 Risk-based flowchart for site characterization 2 CPT Guide - 2010 Cone Penetration Test (CPT) Role of the CPT The objectives of any subsurface investigation are to determine the following: Nature and sequence of the subsurface strata (geologic regime) Groundwater conditions (hydrologic regime) Physical and mechanical properties of the subsurface strata For geo-environmental site investigations where contaminants are possible, the above objectives have the additional requirement to determine: Distribution and composition of contaminants The above requirements are a function of the proposed project and the associated risks. An ideal investigation program should include a mix of field and laboratory tests depending on the risk of the project. Table 2 presents a partial list of the major in-situ tests and their perceived applicability for use in different ground conditions. Table 2. The applicability and usefulness of in-situ tests (Lunne, Robertson & Powell, 1997) 3 CPT Guide - 2010 Cone Penetration Test (CPT) The Cone Penetration Test (CPT) and its enhanced versions (i.e. piezocone- CPTu and seismic-SCPT) have extensive applications in a wide range of soils. Although the CPT is limited primarily to softer soils, with modern large pushing equipment and more robust cones, the CPT can be performed in stiff to very stiff soils, and in some cases soft rock. Advantages of CPT: Fast and continuous profiling Repeatable and reliable data (not operator-dependent) Economical and productive Strong theoretical basis for interpretation Disadvantage of CPT: Relatively high capital investment Requires skilled operators No soil sample, during a CPT Penetration can be restricted in gravel/cemented layers Although it is not possible to obtain a soil sample during a CPT, it is possible to obtain soil samples using CPT pushing equipment. The continuous nature of CPT results provide a detailed stratigraphic profile to guide in selective sampling appropriate for the project. The recommended approach is to first perform several CPT soundings to define the stratigraphic profile and to provide initial estimates of geotechnical parameters, then follow with selective sampling. The type and amount of sampling will depend on the project requirements and risk as well as the stratigraphic profile.
Load more

Recommended publications
  • CPT-Geoenviron-Guide-2Nd-Edition
    Engineering Units Multiples Micro (P) = 10-6 Milli (m) = 10-3 Kilo (k) = 10+3 Mega (M) = 10+6 Imperial Units SI Units Length feet (ft) meter (m) Area square feet (ft2) square meter (m2) Force pounds (p) Newton (N) Pressure/Stress pounds/foot2 (psf) Pascal (Pa) = (N/m2) Multiple Units Length inches (in) millimeter (mm) Area square feet (ft2) square millimeter (mm2) Force ton (t) kilonewton (kN) Pressure/Stress pounds/inch2 (psi) kilonewton/meter2 kPa) tons/foot2 (tsf) meganewton/meter2 (MPa) Conversion Factors Force: 1 ton = 9.8 kN 1 kg = 9.8 N Pressure/Stress 1kg/cm2 = 100 kPa = 100 kN/m2 = 1 bar 1 tsf = 96 kPa (~100 kPa = 0.1 MPa) 1 t/m2 ~ 10 kPa 14.5 psi = 100 kPa 2.31 foot of water = 1 psi 1 meter of water = 10 kPa Derived Values from CPT Friction ratio: Rf = (fs/qt) x 100% Corrected cone resistance: qt = qc + u2(1-a) Net cone resistance: qn = qt – Vvo Excess pore pressure: 'u = u2 – u0 Pore pressure ratio: Bq = 'u / qn Normalized excess pore pressure: U = (ut – u0) / (ui – u0) where: ut is the pore pressure at time t in a dissipation test, and ui is the initial pore pressure at the start of the dissipation test Guide to Cone Penetration Testing for Geo-Environmental Engineering By P. K. Robertson and K.L. Cabal (Robertson) Gregg Drilling & Testing, Inc. 2nd Edition December 2008 Gregg Drilling & Testing, Inc. Corporate Headquarters 2726 Walnut Avenue Signal Hill, California 90755 Telephone: (562) 427-6899 Fax: (562) 427-3314 E-mail: [email protected] Website: www.greggdrilling.com The publisher and the author make no warranties or representations of any kind concerning the accuracy or suitability of the information contained in this guide for any purpose and cannot accept any legal responsibility for any errors or omissions that may have been made.
    [Show full text]
  • Presentation Slides
    Center for Accelerating Innovation Advanced Geotechnical Methods in Exploration (A-GaME) Tools for Enhanced, Effective Site Characterization 1 Center for Accelerating Innovation What are the Advanced Geotechnical Methods in Exploration? The A-GaME is a toolbox of underutilized subsurface exploration tools that will assist with: • Assessing risk and variability in site characterization • Optimizing subsurface exploration programs • Maximizing return on investment in project delivery 2 Center for Accelerating Innovation Why do you need to bring your A-GaME? • Because, in up to 50% of major infrastructure projects, schedule or costs will be significantly impacted by geotechnical issues!! • The majority of these issues will be directly or indirectly related to the scope and quality of subsurface investigation and site characterization work. 3 Center for Accelerating Innovation Presenters Silas Nichols Derrick Dasenbrock Ben Rivers Principal Bridge Geomechanics/LRFD Geotechnical Engineer – Engineer Engineer Geotechnical Minnesota DOT FHWA RC FHWA HQ 4 Center for Accelerating Innovation What is “Every Day Counts”(EDC)? State-based model to identify and rapidly deploy proven but underutilized innovations to: shorten the project delivery process enhance roadway safety reduce congestion improve environmental sustainability . EDC Rounds: two year cycles . Initiating 5th Round (2019-2020) - 10 innovations . To date: 4 Rounds, over 40 innovations For more information: https://www.fhwa.dot.gov/innovation/ FAST Act, Sec.1444 5 Center for Accelerating Innovation Implementation Planning Team Practitioners l Geotechnical l Construction l Design l Risk l Geophysics l Site Variability l Public and Private Sectors l Industry Representation – ADSC, AEG, DFI, EEGS, GI and AASHTO COBS, COC, COMP Brian Collins – FHWA-WFL Michelle Mann – NMDOT Derrick Dasenbrock – MNDOT Marc Mastronardi - GDOT Mohammed Elias – FHWA-EFL Mike McVay – Univ.
    [Show full text]
  • Cone Penetration Test for Bearing Capacity Estimation
    The 2nd Join Conference of Utsunomiya University and Universitas Padjadjaran, Nov.24,2017 CONE PENETRATION TEST FOR BEARING CAPACITY ESTIMATION AND SOIL PROFILING, CASE STUDY: CONVEYOR BELT CONSTRUCTION IN A COAL MINING CONCESSION AREA IN LOA DURI, EAST KALIMANTAN, INDONESIA Ilham PRASETYA*1, Yuni FAIZAH*1, R. Irvan SOPHIAN1, Febri HIRNAWAN1 1Faculty of Geological Engineering, Universitas Padjadjaran Jln. Raya Bandung-Sumedang Km. 21, 45363, Jatinangor, Sumedang, Jawa Barat, Indonesia *Corresponding Authors: [email protected], [email protected] Abstract Cone Penetration Test (CPT) has been recognized as one of the most extensively used in situ tests. A series of empirical correlations developed over many years allow bearing capacity of a soil layer to be calculated directly from CPT’s data. Moreover, the ratio between end resistance of the cone and side friction of the sleeve has been prove to be useful in identifying the type of penetrated soils. The study was conducted in a coal mining concession area in Loa Duri, east Kalimantan, Indonesia. In this study the Begemann Friction Cone Mechanical Type Penetrometer with maximum push 2 capacity of 250 kg/cm was used to determine bearing layers for foundation of the conveyor belt at six different locations. The friction ratio (Rf) is used to classify the type of soils, and allowable bearing capacity of the bearing layers are calculated using Schmertmann method (1956) and LCPC method (1982). The result shows that the bearing layers in study area comprise of sands, and clay- sand mixture and silt. The allowable bearing capacity of shallow foundations range between 6-16 kg/cm2 whereas that of pile foundations are around 16-23 kg/cm2.
    [Show full text]
  • Probabilistic Analysis of Immersed Tunnel Settlement Using CPT and MASW
    Probabilistic analysis of immersed tunnel settlement using CPT and MASW Bob van Amsterdam January 16, 2019 Version: Final report Probabilistic analysis of immersed tunnel settlement using CPT and MASW Bob van Amsterdam Thesis committee: Prof. Dr. ir. K.G. Gavin Geo-engineering TU Delft Assoc. prof. Dr. ir. W. Broere Geo-engineering TU Delft Ir. K.J. Reinders Hydraulic engineering TU Delft Dr. ir. C. Reale Geo-engineering TU Delft January 16, 2019 Abstract Settlement data of the Kiltunnel and the Heinenoordtunnel show that immersed tunnels in the Netherlands have been experiencing much larger settlement than expected when designing the tunnels causing cracks in the concrete and leakages in the joints. Settlements of 8 - 70 mm have been measured at the Kiltunnel and of 7 - 30 mm at the Heinenoordtunnel while settlements in the range of 0 - 1 mm were expected. Both sites are investigated through non-invasive geophysical site investigation method MASW (Multichannel Analysis of Surface Waves) for each 2.5 meter along the length of the tunnel and invasive site characterisation method CPT’s (Cone Penetration Tests). The settlement of immersed tunnels is similar to that of a shallow foundation. It can be modelled using the Mayne equation which uses the small strain shear stiffness and the degradation of secant stiffness based on the load compared to the ultimate bearing resistance. A way of characterising the site is determining the small strain stiffness directly from the shear wave velocity using the uncertainties in the relationship between shear wave velocity and cone penetration resistance and correlating the cone penetration resistance to this value.
    [Show full text]
  • Geotechnical Investigations for Tunneling
    Breakthroughs in Tunneling September 12, 2016 Geotechnical Site Investigations For Tunneling Greg Raines, PE Objective To develop a conceptual model adequate to estimate the range of ground conditions and behavior for excavation, support, and groundwater control. support Typical Phases of Subsurface Investigation Phase 1: Planning Phase – Desk Top Study/Review Phase 2: Preliminary/Feasibility Design – Initial Field Investigations Phase 3: Final Design – Additional/Follow-Up Field Investigations Final Phase: Construction – Continued characterization of site Typical Phases of Subsurface Investigation Phase 1: Planning Phase – Desk Top Study/Review Review: Geologic maps Previous reports/investigations Aerial photos Case histories Develop conceptual geologic/geotechnical model (cross sections), preliminarily identify technical constraints/issues for the project. Plan subsurface investigation program. Identify/Collect Available Geotechnical Data in the Project Area Bridge or control Information can include: structure • Geologic maps • Data from previous reports • Drill hole data • Preliminary mapping Compile available local data into a database for further evaluation. Roads or Residential Canals Area Geologic Profiles – Understand Geologic Setting and Collect Specific Data Bedrock Surface Elevation Maps Aerial Photo / LiDAR Interpretation Aerial Photo Diversion Tunnel Use digital imagery/LiDAR to map local features prior to field mapping. Dam LiDAR Field Geologic Mapping Field Geologic Mapping Structural Data Collection (faults, folds,
    [Show full text]
  • Fugro Cone Penetration Tests
    SERVICE FLYER FUGRO CONE PENETRATION TESTS The objective of all site investigations is to obtain data that will ■■ Piezocones (CPTU) can also be used adequately quantify the variability of the geotechnical properties of to assess hydrostatic head, the site. Cone Penetrometer Testing (CPT) provides a rapid and cost consolidation and permeability effective way to achieve this. characteristics ■■ Yields thousands or tens of thousands of data points that can be digitally INTRODUCTION stored and transferred in real time Sufficient data is required to assess the ■■ Provides a continuous (although ■■ Cost-effective method employing rapid impact of soil variability within a time frame indirect) record of ground conditions, probing rates to accredited test such that it can be allowed for within the avoiding the ground disturbance procedures geotechnical design and/or construction. associated with boring and sampling ■■ Data may be used in long-established CPT generates high value data and adapts CPT units can be mobilised as road-going semi-empirical design methods, for readily to the environmental sensitivities of 6x6 trucks or a variety of tracked and example, analysis of foundation many investigations in favourable types of crawler units, ideally suited to traversing bearing capacity, foundation material, generally excluding bedrock, very soft, water logged terrain or entering sites settlement, pile carrying capacity and dense granular fill and strata containing with limited access. Fugro’s development of liquefaction potential cobbles and boulders.
    [Show full text]
  • NOTES on the CONE PENETROMETER TEST
    GE 441 Advanced Engineering Geology & Geotechnics Spring 2004 NOTES on the CONE PENETROMETER TEST Introduction The standardized cone-penetrometer test (CPT) involves pushing a 1.41-inch diameter 55o to 60o cone (Figs. 1 thru 3) through the underlying ground at a rate of 1 to 2 cm/sec. CPT soundings can be very effective in site characterization, especially sites with discrete stratigraphic horizons or discontinuous lenses. Cone penetrometer testing, or CPT (ASTM D-3441, adopted in 1974) is a valuable method of assessing subsurface stratigraphy associated with soft materials, discontinuous lenses, organic materials (peat), potentially liquefiable materials (silt, sands and granule gravel) and landslides. Cone rigs can usually penetrate normally consolidated soils and colluvium, but have also been employed to characterize d weathered Quaternary and Tertiary-age strata. Cemented or unweathered horizons, such as sandstone, conglomerate or massive volcanic rock can impede advancement of the probe, but the author has always been able to advance CPT cones in materials of Tertiary-age sedimentary rocks. The cone is able to delineate even the smallest (0.64 mm/1/4-inch thick) low strength horizons, easily missed in conventional (small-diameter) sampling programs. Some examples of CPT electronic logs are attached, along with hand-drawn lithologic interpretations. Most of the commercially-available CPT rigs operate electronic friction cone and piezocone penetrometers, whose testing procedures are outlined in ASTM D-5778, adopted in 1995. These devices produce a computerized log of tip and sleeve resistance, the ratio between the two, induced pore pressure just behind the cone tip, pore pressure ratio (change in pore pressure divided by measured pressure) and lithologic interpretation of each 2 cm interval are continuously logged and printed out.
    [Show full text]
  • The Application of the Seismic Cone Penetration Test (SCPTU) in Tailings Water Conditions Monitoring
    Article The Application of the Seismic Cone Penetration Test (SCPTU) in Tailings Water Conditions Monitoring Wojciech Tschuschke 1, Sławomir Gogolik 1, Magdalena Wró˙zy´nska 1,* , Maciej Kroll 1 and Paweł Stefanek 2 1 Institute of Construction and Geoengineering, Pozna´nUniversity of Life Sciences, Wojska Polskiego 28, 60–637 Pozna´n,Poland; [email protected] (W.T.); [email protected] (S.G.); [email protected] (M.K.) 2 Tailings Management Division, KGHM Polska Mied´z,Polkowicka 52, 59-305 Rudna, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-6-1846-6453 Received: 15 January 2020; Accepted: 5 March 2020; Published: 8 March 2020 Abstract: The safe operation of the large, outflow Tailings Storage Facilities (TSF) requires comprehensive and continuous threat monitoring. One of the basic kinds of threat monitoring is to monitor the water conditions in deposited tailings, which is usually carried out using a conventional piezometric observation method from a network of installed piezometers. In complex tailings storage conditions, the reliability of the piezometric method may be questioned. The Seismic Cone Penetration Test (SCPTU) can meet high test standards. The results of the penetration tests closely identify conditions of sediments that determine the tailings water regime verified locally on the basis of pore water pressure dissipation tests. On the other hand, seismic measurements perfectly complement the characteristics of sediments in terms of their saturation. The analysis of the results of SCPTU implemented in the tailings massif also showed that below the phreatic surface, a zone of not fully saturated tailings can be found.
    [Show full text]
  • Differential Settlement of Foundations on Loess
    Missouri University of Science and Technology Scholars' Mine International Conference on Case Histories in (2013) - Seventh International Conference on Geotechnical Engineering Case Histories in Geotechnical Engineering 02 May 2013, 2:00 pm - 3:30 pm Differential Settlement of Foundations on Loess Dušan Milović University of Novi Sad, Serbia Mitar Djogo University of Novi Sad, Serbia Follow this and additional works at: https://scholarsmine.mst.edu/icchge Part of the Geotechnical Engineering Commons Recommended Citation Milović, Dušan and Djogo, Mitar, "Differential Settlement of Foundations on Loess" (2013). International Conference on Case Histories in Geotechnical Engineering. 10. https://scholarsmine.mst.edu/icchge/7icchge/session02/10 This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License. This Article - Conference proceedings is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in International Conference on Case Histories in Geotechnical Engineering by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. DIFFERENTIAL SETTLEMENT OF FOUNDATIONS ON LOESS Dušan Milović Mitar Djogo University of Novi Sad University of Novi Sad Novi Sad, SERBIA Novi Sad, SERBIA ABSTRACT Experience gained during several decades shows that the loess soil in some cases undergoes structural collapse and subsidence due to inundation and that in some other cases the sensitivity of loess to the collapse is considerably less pronounced. In this paper the behaviour of three 12 story buildings A, B and C, of the same static system and the identical shapes have been analyzed.
    [Show full text]
  • Some Issues Related to Applications of the CPT
    2nd International Symposium on Cone Penetration Testing, Huntington Beach, CA, USA, May 2010 Some issues related to applications of the CPT N. Ramsey Sinclair Knight Merz, Melbourne, Australia ABSTRACT: This paper reviews some issues related to the use of Cone Penetration Testing for geotechnical applications. Some of the areas that are considered include: a) The advantages and disadvantages of Cone Penetration Testing (CPT) b) The advantages of integrating CPT with laboratory testing. c) Identification of similar geological units using statistics. d) A review of published classification/behaviour charts, using a diverse and highly dependable database. e) The importance of using correct cone calibration and cone zero values in normally consolidated fine-grained soils. 1 INTRODUCTION The Burland Triangle (Burland, 1987), shown in Figure 1, provides a useful framework for the majority of geotechnical problems. The Cone Penetration Test (CPT) can provide valuable input to this framework, by providing cost-effective and useful information for the “Ground profile” and “Soil behaviour” aspects of the triangle. Figure 1: The Burland Triangle (Burland, 1987) The main purposes of this paper are to review the contribution of the CPT, in terms of ground profiling and the assessment of soil behaviour. The paper concentrates primarily on sites containing normally consolidated (NC) fine grained soils, as these soils tend to be relatively difficult to analyse, and because published correlations can be less reliable in these soils. Practical examples
    [Show full text]
  • Interpretation of Seismic Cone Penetration Testing in Silty Soil
    Interpretation of Seismic Cone Penetration Testing in Silty Soil Rikke Holmsgaard1, Lars Bo Ibsen2, and Benjaminn Nordahl Nielsen3 1PhD. Fellow, Master of Science in Civil Engineering, Aalborg University, Department of Civil Engineering, Sofiendalsvej 11, 9200 Aalborg SV, Denmark, Phone +45 40939994, email: [email protected] 2Professor, Aalborg University, Department of Civil Engineering, Sofiendalsvej 11, 9200 Aalborg SV, Denmark, Phone +45 99408458, email: [email protected] 3Associate Professor, Aalborg University, Department of Civil Engineering, Sofiendalsvej 11, 9200 Aalborg SV, Denmark, Phone +45 99408459, email: [email protected] Corresponding author: Rikke Holmsgaard, email: [email protected] ABSTRACT Five Seismic Cone Penetration Tests (SCPT) were conducted at a test site in northern Denmark where the subsoil consists primarily of sandy silt with clay bands. A portion of the test data were collected every 0.5 m to compare the efficacy of closely-spaced down-hole data collection on the computation of shear wave velocity. A minimum of eight seismic tests were completed at each depth in order to examine the reliability of shear wave velocity data, as well as to assess the impact of the time interval between CPT termination and seismic test initiation on SCPT results. The shear wave velocity was computed using three different methods: cross-over, cross-correlation and cross-correlation “trimmed with window”. In the “trimmed with window” technique the latter part of the signal is clipped off by setting the amplitude to zero. The result showed that more closely-spaced test intervals actually increased the variability of the shear wave velocity and that time interval between seismic tests is insignificant.
    [Show full text]
  • Seismic Cone Penetration Test and Vertical Seismic Profiling in Permafrost
    Permafrost, Phillips, Springman & Arenson (eds) © 2003 Swets & Zeitlinger, Lisse, ISBN 90 5809 582 7 Seismic cone penetration test and vertical seismic profiling in permafrost A.-M. LeBlanc & R. Fortier Département de géologie et de génie géologique and Centre d’études nordiques, Université Laval, Sainte-Foy (Québec), Canada M. Allard Département de géographie and Centre d’études nordiques, Université Laval, Sainte-Foy (Québec), Canada ABSTRACT: Seismic Cone Penetration Tests (SCPTs) were carried out to a depth of 24 m in a permafrost mound near the Inuit community of Umiujaq in Nunavik, Canada, to study its cryostratigraphy in terms of pene- tration resistance and seismic velocities. The tip load, friction, temperature, inclination and electrical resistivity were measured with sensors embedded in the penetrometer. The cone penetration was stopped periodically to add a new rod and to perform multi-offset Vertical Seismic Profiling (VSP). A Swept Impact Seismic Technique (SIST) was used as a seismic source directly in contact with the thawing front and the seismic signal was recorded with a module of triaxial accelerometers, also embedded in the penetrometer, and with a seismograph. The seis- mic velocities were evaluated from the propagation time of the seismic signal in permafrost. The permafrost con- ditions are characterised by variation in seismic velocities with depth, depending on the ground temperature and sequence of frozen soil layers and ice lenses. 1 INTRODUCTION 2 STUDY SITE The study of the dynamic behaviour of frozen soils is The fieldwork was conducted on the east coast of the fundamental in cold regions engineering for the Hudson Bay, near the Inuit community of Umiujaq design of vibrating machinery on frozen ground, the (56°N, 76°W) in Nunavik, Canada, in the discontinu- response of frozen soil to dynamic loading induced by ous and scattered permafrost zone (Fig.
    [Show full text]